Varying a numerical aperture of a laser during lens fragmentation in cataract surgery

ABSTRACT

Some embodiments disclosed here provide for a method fragmenting a cataractous lens of a patient&#39;s eye using an ultra-short pulsed laser. The method can include determining, within a lens of a patient&#39;s eye, a high NA zone where a cone angle of a laser beam with a high numerical aperture is not shadowed by the iris, and a low NA zone radially closer to the iris where the cone angle of the laser beam with a low numerical aperture is not shadowed by the iris. Laser lens fragmentation is accomplished by delivering the laser beam with the high numerical aperture to the high NA zone, and the laser beam with the low numerical aperture to the low NA zone. This can result in a more effective fragmentation of a nucleus of the lens without exposing the retina to radiation above safety standards.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalApplication No. 61/794,359, filed Mar. 15, 2013, the entire content ofwhich is incorporated herein by reference.

BACKGROUND

1. Field

Embodiments of this invention generally relate to laser cataractsurgery, and more particularly to a method of laser-assisted lensfragmentation.

2. Description of Related Art

Eye disease can impair a patient's vision. For example, a cataract canincrease the opacity of an ocular lens, and eventually, cause blindness.To restore the patient's vision, the diseased lens may be surgicallyremoved and replaced with an artificial lens, known as an intraocularlens, or IOL. A number of medically recognized techniques are utilizedfor removing a cataractous lens based on, for example,phacoemulsification, mechanical cutting or destruction, lasertreatments, water jet treatments, and so on.

A typical cataract surgery involves removing the eye's natural lenswhile leaving in place the back of the capsule which holds the lens inplace. Using certain procedures, such as laser treatments along withphacoemulsification, for example, the cataract can be broken into tinypieces that can be removed from the eye through a relatively smallincision. In cataract surgery using phacoemulsification, the surgeonmakes a small incision in the white portion of the eye near the outeredge of the cornea. An ultrasonic probe is then inserted through thisopening and ultrasonic frequencies are used to break up the cataractinto tiny pieces. The emulsified material can be simultaneouslysuctioned from the eye, typically using the open tip of the sameinstrument. To reduce the amount of ultrasonic energy used to break upthe cataract, the lens can be softened and/or fragmented using a laserprior to application of ultrasonic energy. As such, the hard centralcore of the cataract (the nucleus) is removed first, followed byextraction of the softer, peripheral cortical fibers that make up theremainder of the lens. As compared to other forms of cataract surgery,laser-assisted cataract provides faster healing and rehabilitation aswell as reduced discomfort.

SUMMARY

In laser-assisted cataract surgery, laser lens fragmentation can be usedto pre-cut or fragment the eye lens before it is removed. A surgicallaser, such as a non-ultraviolet, ultra-short pulsed laser that emitsradiation with pulse durations as short as nanoseconds and femtoseconds(e.g., a femtosecond laser, or a picosecond laser) can be used to cutthe lens of the patient's eye into pieces. These pieces can then beremoved through a small incision in the eye. Typically, to reduce theoverall amount of energy delivered to the eye surgery, laser lensfragmentation is performed prior to phacoemulsification. Laser systemscapable of generating ultra-short pulsed laser beams are disclosed infor example, U.S. Pat. No. 4,764,930 and U.S. Pat. No. 5,993,438, whichare incorporated here by reference. In some situations, fragmenting alens with a laser can reduce the amount of cumulative dispersive energy(CDE) used for phacoemulsification than is used for a non-laser-treatedcataractous lens. The reduction in CDE can depend at least in part onthe grade of the cataract, where a higher grade cataract can be moredifficult to cut and/or remove. For example, laser lens fragmentationmay be able to completely fragment a grade 1 nuclear cataract (e.g., nophacoemulsification required, or a 100% reduction in CDE), while CDE maybe reduced by about 40% to 50% for a grade 4 nuclear cataract. Areduction in the amount of CDE during phacoemulsification can generallybe desirable because phacoemulsification can be one of the key causes ofcomplications related to cataract surgery, including for example,posterior capsular breaks and/or corneal edema.

One limitation on the efficacy of laser lens fragmentation forhigher-grade nuclear cataracts may be related to safety standards.Regulations place limits on the amount of energy that can be deliveredto the retina of a patient's eye, and these limits are based at least inpart on safety considerations. The limits are designed to reduce orprevent permanent or debilitating damage to the retina during laserprocedures. The amount of energy or power delivered to the retina duringa laser procedure is based at least in part on the energy of the laserand a numerical aperture of the laser beam.

Another factor affecting the efficacy of laser lens fragmentation isrelated to shadowing effects by the iris. The extent of the volume oftissue that can be treated using a laser beam can depend at least inpart on a desire to not deliver laser energy to the iris. When a laseris focused onto a targeted focal spot, the incoming laser beam has asubstantially conical shape. Hence, the larger the numerical aperture ofthe laser beam, the larger is the opening angle of the cone.Accordingly, when the target volume is past the iris, the potentialtreatment volume decreases as the numerical aperture of the laser beamincreases.

Typical systems and methods have been designed to find a balance betweensafety, iris shadowing, laser lens fragmentation efficacy, cost, andcomplexity. To increase or maximize the treatment volume, these systemsand methods generally use a relatively low numerical aperture (e.g.,about 0.125) of the laser beam. The choice of the relatively lownumerical aperture affects the maximum amount of laser energy that canbe used, because, as described, a reduction in numerical apertureincreases the energy delivered to the retina for a given laser energy.The relatively low numerical aperture and the resultant laser energyaffect how effectively the laser fragments a nucleus of a cataract. Forexample, using a relatively low numerical aperture, some of the moreeffective laser cataract surgery systems have been able to reduce theamount of CDE during phacoemulsification for grade 3 or 4 nuclearcataracts by about 40% to about 50%.

Embodiments of the systems and methods described here can increase theefficacy and efficiency of laser lens fragmentation and/or reduce theamount of CDE used for ultrasonic-breaking of cataracts by using a laserbeam with a numerical aperture that varies as a function of a targetedlocation within the lens. By using a relatively high numerical aperturein a central region of the lens and a relatively low numerical aperturein a peripheral region of the lens, the potential treatment volume canbe the same, or greater than, previous systems' treatment volume whileapplying a greater amount of energy to the nucleus of the cataract. Thiscan result in a greater efficacy in breaking or fragmenting cataracts,and particularly high grade nuclear cataracts, thereby reducing theamount of CDE during phacoemulsification, or eliminating the need forphacoemulsification altogether.

In one aspect, the embodiments disclosed here provide for systems andmethods for fragmenting a lens by varying a numerical aperture of alaser beam. In a first, central region of the lens, a relatively highnumerical aperture laser beam is used, and in a second, peripheralregion of the lens, a lower numerical aperture laser beam is used. Thehigh numerical aperture laser beam can be used to focus more energy inthe central region of the lens, where cataracts can be more difficult tofragment. The higher energy can be due at least in part to a greateramount of energy at the focus of the laser beam. The higher energy ofthe high numerical aperture laser beam can also be configured to notviolate safety restrictions, as the higher numerical aperture deliversless power to the retina than a lower numerical aperture laser beam withcomparable energy. The low numerical aperture laser beam can be usednear the iris to increase the treatment volume without delivering laserenergy to the iris. The low numerical aperture laser beam can beconfigured to effectively fragment this portion of the lens using lessenergy than the high numerical aperture laser beam due at least in partto cataracts being typically softer and easier to fragment near theperiphery. Accordingly, the method can be used to more effectivelyfragment a lens within a similar volume when compared to conventionalsystems.

In another aspect, a method of performing a laser lens fragmentationprocedure is provided where the method includes measuring features of aneye of a patient to find a total laser treatment region. The methodincludes determining: a safety zone comprising a region of the eye ofthe patient which will not receive focused laser radiation; a highnumerical aperture (“NA”) zone, the high NA zone comprising a regionwhere a cone angle of a laser beam with a high numerical aperture is notshadowed by an iris of the patient's eye; and a low NA zone, the low NAzone comprising a region radially closer to the iris than the high NAzone where the cone angle of the laser beam with a low numericalaperture is not shadowed by the iris. The method includes performinglaser lens fragmentation by delivering the laser beam with the highnumerical aperture to the high NA zone, and delivering the laser beamwith the low numerical aperture to the low NA zone. In the method, thehigh NA zone, the low NA zone, and the safety zone can be configured tooccupy, in aggregate, approximately the entirety of the total lasertreatment region.

In some implementations, the high numerical aperture is greater than orequal to about 0.25 and/or the low numerical aperture is less than orequal to about 0.15. In some implementations, measuring features of aneye of a patient includes measuring a pupil diameter, an anteriorboundary, or a posterior boundary of a lens of the patient's eye.

In some implementations, the safety zone is a region of the lens of thepatient's eye that includes a volume that is at least about 0.5 mminwards from an edge of an iris of the patient's eye and at least about0.5 mm from an anterior lens capsule and at least about 0.5 mm from aposterior lens capsule.

In another aspect, a laser cataract surgery control system is provided.The system includes a controller comprising one or more physicalprocessors. The system also includes a fragmentation module configuredto use the one or more physical processors to determine a laser lensfragmentation treatment plan. To determine the laser fragmentationtreatment plan, the laser fragmentation module determines a first regionof a lens of a patient's eye to receive a laser beam having a firstnumerical aperture and a second region of the lens of the patient's eyeto receive a laser beam having a second numerical aperture, the secondnumerical aperture being lower than the first numerical aperture, andthe second region being radially closer, on average, to an iris of thepatient's eye than the first region. The system includes a laser controlmodule in communication with a laser source. The laser control module isconfigured to control the laser source to deliver the laser beam havingthe first numerical aperture and a first energy to the first region ofthe lens, and to control the laser source to deliver the laser beamhaving the second numerical aperture and a second energy to the secondregion of the lens. The first numerical aperture and the first energyare configured to deliver a first peak laser energy to a retina of thepatient's eye that is less than or equal to a safety threshold.

In some implementations, the second numerical aperture and the secondenergy are configured to deliver a second peak laser energy to theretina that is less than or equal to a safety threshold. In someembodiments, the safety threshold is determined based at least partly ona safety standard involving a maximum permissible radiant exposure. Insome implementations, the safety standard conforms to ANSI Z136.1-2000Standard.

In some implementations, the system further includes an image processingmodule in communication with an imaging system. The image processingmodule is configured to: receive an image of the patient's eye;determine, using the at least one physical processor, a size of a pupilof the patient's eye; and determine, using the at least one physicalprocessor, a relative location and size of the lens of the patient'seye. In some implementations, the imaging system is an optical coherencetomography system. In some implementations, the fragmentation module isconfigured to receive the size of the pupil and the size of the lens ofthe patient's eye from the image processing module, wherein thefragmentation module is configured to use the size of the pupil and thesize of the lens to determine the first region and the second region.

In some implementations, the first region is configured to maximize avolume in the lens where the laser beam having the first numericalaperture is used to perform laser lens fragmentation, wherein a maximumradius of the first region from the center of the lens of the patient'seye is determined by a shadowing effect caused by the iris of thepatient's eye.

In some implementations, the fragmentation module is further configuredto determine a third region of the lens of the patient's eye to receivethe laser beam having a third numerical aperture, the third region beingbetween the first region and the second region, and the third numericalaperture being less than the first numerical aperture and greater thanthe second numerical aperture.

In some implementations, the first numerical aperture is equal to about0.3 and/or the second numerical aperture is equal to about 0.125. Insome implementations, after delivery of the laser beam with the firstnumerical aperture to the first region, and after delivery of the laserbeam with the second numerical aperture to the second region, the lensof the patient's eye is sufficiently fragmented such that nophacoemulsification is required to remove the fragmented portion of thelens.

In another aspect, a method of performing a laser lens fragmentationprocedure is provided. The method includes determining, using at leastone physical processor, a first region of a lens of a patient's eye toreceive a laser beam having a first numerical aperture. The methodincludes determining, using the at least one physical processor, asecond region of the lens of the patient's eye to receive a laser beamhaving a second numerical aperture, the second numerical aperture beinglower than the first numerical aperture, and the second region beingradially closer, on average, to an iris of the patient's eye than thefirst region. The method includes controlling a laser source to deliverthe laser beam having the first numerical aperture and a first energy tothe first region of the lens. The method includes controlling the lasersource to deliver the laser beam having the second numerical apertureand a second energy to the second region of the lens. The firstnumerical aperture and the first energy are configured to deliver a peaklaser energy to a retina of the patient's eye that is less than a safetythreshold.

In some implementations, after delivery of the laser beam with the firstnumerical aperture to the first region and after delivery of the laserbeam with the second numerical aperture to the second region, the lensof the patient's eye is sufficiently fragmented such that nophacoemulsification is required to remove the fragmented portion of thelens. In a further implementation, the lens of the patient's eyecomprises a grade 3 nuclear cataract.

BRIEF DESCRIPTION OF THE DRAWINGS

Details of one or more implementations of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings, and the claims. Thedrawings depicting novel and non-obvious aspects of the invention arefor illustrative purposes only. Note that the relative dimensions of thefollowing figures may not be drawn to scale. The drawings include thefollowing figures in which like numerals refer to like parts.

FIG. 1 illustrates a diagram of a human eye illustrating various partsof the eye.

FIG. 2A illustrates a representation of performing a lens fragmentationprocedure using a varying numerical aperture.

FIG. 2B illustrates a representation of laser energy delivered to aretina for laser beams having different numerical apertures.

FIG. 2C illustrates a representation of a shadowing of the iris forlaser beams having different numerical apertures.

FIGS. 3A-3C illustrate example laser systems that can be used to providea varying numerical aperture for use with some embodiments of a lensfragmentation procedure.

FIG. 4 illustrates an example laser cataract surgery control system.

FIG. 5 illustrates a flow chart of an example laser fragmentationprocedure.

DETAILED DESCRIPTION

It is to be understood that the figures and descriptions of the presentinvention have been simplified to illustrate elements that are relevantfor a clear understanding of the present invention, while eliminating,for the purpose of clarity, many other elements found in typical lasercataract surgery systems. Those of ordinary skill in the arts canrecognize that other elements and/or steps are desirable and may be usedin implementing the embodiments described here.

Laser Lens Fragmentation

FIG. 1 is a schematic drawing of a human eye 100. Light enters the eyefrom the left of FIG. 1, and passes through the cornea 110, the anteriorchamber 120, a pupil defined by the iris 130, and enters lens 140. Afterpassing through the lens 140, light passes through the vitreous chamber150, and strikes the retina 160, which detects the light and converts itto a signal transmitted through the optic nerve 170 to the brain (notshown).

Laser cataract surgery involves the removal of an opacified crystallinelens 140 through an incision in the cornea 110. During laser cataractsurgery, a laser can be used to segment and fragment a portion of thelens 140 for removal through the corneal incision. The nucleus 145 ofthe cataract can be a region of the lens which is harder than thesurrounding lens 140. It may be advantageous, as described here, todeliver a greater amount of laser energy to points within the nucleus145 for effective tissue separation and fragmentation.

Described below are systems and methods used to determine a lasertreatment plan and to perform laser lens fragmentation according to thetreatment plan. Determining the treatment plan can include, for example,mapping regions of the lens for delivery of laser energy with varyingnumerical apertures. For example, two zones can be defined in thetreatment plan where a laser beam with a first numerical aperture and afirst energy is delivered to the first zone and the laser beam with asecond numerical aperture and a second energy is delivered to the secondzone. As described in further detail here, any number of zones can bedefined in the treatment plan, and, in some embodiments, a continuouslyvariable numerical aperture can be used to deliver laser energy wherethe laser beam has a numerical aperture and laser energy that aresubstantially continuous functions of position within the lens 140.

FIG. 2A illustrates a representation of a laser lens fragmentationprocedure performed using laser beam with different numerical aperturesin different regions of the lens. A cross-section view of the eye 100 isshown along with the cornea 110, the anterior chamber 120, the iris 130,and the lens 140 having lens nucleus 145. The illustration also shows arepresentation of a laser beam 205 with a relatively high NA and a laserbeam 215 with a relatively low numerical aperture. The high NA laserbeam 205 is shown to have a focus at a point 207 within a high NA zone210. The low NA laser beam 215 is shown to have a focus at a point 217within a low NA zone 220. A safety zone 230 is also shown where thesafety zone is designated as a region in the lens 140 where focusedlaser energy is not delivered.

The laser lens fragmentation procedure, as shown, defines two regionswithin the lens for receiving laser beams of different numericalapertures. The high NA zone 210 comprises a central portion of the lens140. The high NA zone 210 can include at least a portion of the lensnucleus 145 where the lens tissue is often harder and more difficult tofragment or cut. The high NA zone 210 can be determined by analyzing astructure of the patient's eye, as described here. The high NA zone 210is shown to be substantially cylindrical, but other shapes may beappropriate including ellipsoids, spheres, cubes, irregular shapes, andthe like. For example, based at least in part on an analysis of thepatient's eye and the cataract, the high NA zone 210 can be defined tocover portions of the cataract expected to be harder than otherportions. The high NA zone 210 can include these areas so that the highNA laser beam 205 can be used to fragment, crack, or cut these portionsof tissue because a greater energy can be delivered through the high NAlaser beam 205. The high NA laser beam 205 can have a numerical aperturethat is at least about 0.2 and/or less than or equal to about 0.6, atleast about 0.25 and/or less than or equal to about 0.55, at least about0.3 and/or less than or equal to about 0.5, or at least about 0.3 andless than or equal to about 0.4.

The low NA zone 220 comprises a peripheral region surrounding the highNA zone 210. The low NA zone 220 can be configured to be radially closerto the iris 130, as measure from a central portion of the lens 140 oreye. This region may be softer and/or easier to cut relative to thecentral portion of the lens 140 or the lens nucleus 145. As describedhere with reference to FIGS. 2B and 2C, the low NA laser beam 215 may bedelivered using an energy that is less than the energy of the high NAlaser beam 205 and still sufficiently fragment the lens for removal. Insome embodiments, the lower energy is used due in part to safetyconsiderations related to laser energy on the retina 160, as describedin greater detail with reference to FIG. 2B. The low NA laser beam 215may be advantageously configured to fragment the lens in a zone that isradially further from the center of the lens 140 compared to the high NAzone 210, allowing for a larger volume to be fragmented as describedhere with reference to FIG. 2C. By reducing the numerical aperture ofthe laser beam, the amount of energy delivered to the retina increasesfor a given laser energy. This can lead to damage to the retina if thelaser energy at the retina exceeds damage thresholds. In someembodiments, the laser energy can be reduced for the low NA laser beam215 to conform to safety standards. Due in part to the material near theperiphery of the lens 140 being generally softer, the reduced laserenergy in the low NA beam 215 may be able to fragment the lens 140 inthe low NA region 220. In some embodiments, the low NA zone 220 isannular in shape and is adjacent to the high NA zone 210. Other shapesand configurations are possible as well. The low NA zone 220 can beconfigured to cover, in aggregate with the high NA zone 210 and thesafety zone 230, the entire treatment volume. The low NA laser beam 215can have a numerical aperture that is at least about 0.075 and/or lessthan or equal to about 0.25, at least about 0.1 and/or less than orequal to about 0.2, at least about 0.125 and/or less than or equal toabout 0.175, or at least about 0.125 and less than or equal to about0.15.

The safety zone 230 comprises a region of the lens that is designated tonot receive any focused laser radiation during lens fragmentation. Thesafety zone 230 can be defined as a boundary around the edge of the lens140 configured to provide a buffer zone to reduce or eliminate potentialdamage to the anterior lens capsule, the posterior lens capsule, and/orthe iris. The safety zone 230 can be for example, about 0.5 mm inwardsfrom the iris edges, from the anterior lens capsule, and/or theposterior lens capsule. In some embodiments, the safety zone is at leastabout 0.1 mm and/or less than or equal to about 2 mm from thesestructures, at least about 0.25 mm and/or less than or equal to about 1mm from these structures, or at least about 0.3 mm and/or less than orequal to about 0.75 mm from these structures.

Changing the numerical aperture of the laser beam can change the energydelivered at the focal region for a given laser energy (e.g., a constantpulse energy in a pulsed laser system). For a given laser energy, theenergy at the high NA focus 207 will be greater than the energy at thelow NA focus 217 by a factor, where the factor is roughly equal to thesquare of the ratio of the high numerical aperture to the low numericalaperture. For example, if the high NA laser beam 205 has a numericalaperture of about 0.3 and the low NA laser beam 215 has a numericalaperture of about 0.15, the energy delivered to the high NA focus spot207 is roughly four times the energy delivered to the low NA focus spot217 for a given laser energy. Accordingly, compared to systems with afixed numerical aperture laser beam with a relatively low NA, thesystems and methods here can be configured to deliver a greater laserenergy to the lens nucleus 145 which may be advantageous to fragmenthigh grade nuclear cataracts. As a specific example, Table 1 comparesthe energy threshold for lens tissue separation for a NA of 0.4 and a NAof 0.12 for different spot-line sizes. It can be seen that high NA canuse less energy to achieve lens tissue separation when compared to lowNA.

Spot-Line NA = 0.4 NA = 0.12 5 μm × 5 μm 1.5 μJ >8 μJ 6 μm × 6 μm 1.5μJ >8 μJ 7 μm × 7 μm 2.0 μJ >8 μJ 8 μm × 8 μm 3.0 μJ >8 μJ 9 μm × 9 μm3.5 μJ >8 μJ 10 μm × 10 μm 7.5 μJ >8 μJ

One limitation on the energy that can be used in a laser system used toperform laser lens fragmentation is based at least in part on safetystandards related to the amount of energy delivered to a patient'sretina. FIG. 2B illustrates a representation of laser energy deliveredto a retina 160 for laser beams having different numerical apertures.The illustration on the left shows that for a high NA laser beam 205 thelaser energy delivered to the retina 160 is spread out over a largerarea when compared to the illustration on the right depicting a low NAlaser beam 215. For a given laser energy, this means that the amount ofenergy delivered to the retina 160 decreases with an increase innumerical aperture. The maximum laser exposure at the retina 160 isapproximately proportional to 1/NA². Accordingly, for a given maximumlaser exposure, the high NA laser beam 205 can have an energy that isgreater than the low NA laser beam 215. For example, if the high NAlaser beam 205 has a numerical aperture of about 0.3 and the low NAlaser beam 215 has a numerical aperture of about 0.15, the high NA laserbeam 205 can have an energy that is roughly four times greater than thelow NA laser beam 215 and deliver roughly the same maximum laser energyto the retina 160. Combining this with the laser focus energyconsiderations above, means that using the high NA laser beam 205 withinthe high NA zone 210 and the low NA laser beam 215 in the low NA zone220 can result the energy being delivered to the high NA focus 207 beinga factor of NA⁴ greater than the energy being delivered to the low NAfocus 217 while abiding by safety standards.

The safety standards can be based on concerns with damaging a retina orother areas of the patient's eye. The damage may arise from thermaleffects, microbubble formation, mechanical shockwave damage fromoverheating melanosomes, or other similar effects. Regulatory bodies,lawmakers, or other standards-setting organizations establish guidelinesfor defining a recommended amount of power delivered to reduce orminimize potential damage to the patient's eye. For example, ANSIstandard Z136.1-2007 and ISO 15004-2:2007 provide guidance for the safeuse of lasers, and have been used to set safety standards for laser usein medical devices, such as ophthalmic surgical systems. These standardscan be subject to model-dependent calculations, depending on laserwavelength, retinal beam radius, laser pulse duration, laser pulsefrequency, and the like. For example, in laser cataract surgery using anultra-short pulsed laser, the safety guidelines suggest that for a pulserate greater than about 20 kHz, a wavelength of between about 1030 nmand about 1064 nm, the derived maximum permissible exposure (MPE) forretina safety is about 9.4*t^(−0.25) W/cm^2, where t is the laserexposure time. The peak intensity at the retina, which is inverselyproportional to the square of the numerical aperture, should beconfigured to be lower than the derived MPE. Thus, in some embodiments,the numerical aperture and laser energy can be selected to conform to asafety threshold, such as the derived MPE.

Another factor in determining a laser treatment plan is a plannedtreatment volume. FIG. 2C illustrates a representation of shadowing bythe iris for laser beams having different numerical apertures. It may bedesirable or advantageous to avoid delivering laser energy to the iris130 to reduce or eliminate potential injury to the iris 130. A laserbeam with a higher NA has a larger opening angle, forming a cone that isbroader than a laser beam with a lower NA. The illustration shows thehigh NA laser beam 205 with the high NA focus 207 and the low NA laserbeam 215 with the low NA focus 217 at roughly the same depth 209 behindthe iris 130. At this depth, the position of the high NA focus 207 isradially closer to the center of the lens 140 compared to the low NAfocus 217. The high NA laser beam 205 would contact the iris 130 if itwere to move to the left in the illustration. Thus, the treatment volumefor the high NA laser beam 205 would not be able to include points moreperipheral than the point represented by the high NA focus 207. It maybe desirable, however, to extend the treatment volume towards the iris130. This can be accomplished, as illustrated, by lowering the numericalaperture of the laser beam. For example, the low NA laser beam 215 canbe focused at low NA focus 217, which is more peripheral than the highNA focus 207. Accordingly, referring back to FIG. 2A, the high NA zone210 can include all points that are radially closer to the center of thelens than the high NA focus 207 shown in FIG. 2C. Similarly, referringback to FIG. 2A, the low NA zone 220 can include all points that areradially closer to the center of the lens than the low NA focus 217 andthat are radially further from the lens than the high NA focus. Asdescribed here, the shapes or configurations of the various zonesassociated with laser beams of varying numerical apertures need not becylindrical or annular. In some embodiments, the shadowing of the iris130 can result in the shape of a zone to be circular at a particulardepth, which is based on the geometry of the patient's eye.

In some embodiments, when formulating a treatment plan for laser lensfragmentation, multiple treatment zones can be identified, determined,and/or delineated. The various treatment zones can be based at least inpart on some combination of safety considerations, iris shadowing,cataract characteristics (e.g., cataract grade), a structure of thepatient's eye, a desired or selected amount of energy to deliver to alocation, and the like. As described, the treatment plan includedidentifying two zones for laser delivery using two numerical apertures.In some embodiments, the treatment plan can include three zones, fourzones, five zones, six zones, or more than six zones. In someembodiments, the treatment plan can include using three numericalapertures, four numerical apertures, five numerical apertures, sixnumerical apertures, or more than six numerical apertures. In someembodiments, the treatment plan can include a planned or desired laserenergy and/or numerical aperture as a function of position within thelens 140. The function can be substantially continuous or it can bediscrete, having any number of suitable steps in value as a function ofposition. The treatment plan can vary with depth within the lens and/oras a function of radial position from a central axis through the lens140.

In some embodiments, the laser lens fragmentation methods and systemsdescribed here can be used to reduce an amount of CDE duringphacoemulsification. In some embodiments, the reduction in the amount ofCDE during phacoemulsification for grade 3 cataracts can be greater thanabout 50%, greater than about 60%, greater than about 70%, greater thanabout 80%, greater than about 90%, or about 100%. In some embodiments,the step of performing phacoemulsification can be eliminated through theuse of the systems and methods described here. For example, sufficientlaser energy can be delivered to a lens to sufficiently cut the lenssuch that the fragmented lens can be aspirated without applying anyultrasonic energy. This can advantageously remove thephacoemulsification step, which can be the only step in a laser cataractprocedure that involves the application of energy not from a laser.Thus, in some embodiments, the entire laser cataract surgery can beperformed using laser energy. Typical systems are configured to softenlenses for phacoemulsification, and have been shown to be unable tocrack high grade cataracts. For example, performing laser lensfragmentation on a grade 3 or grade 4 nuclear cataract with a typicalsystem, phacoemulsification is still required after application of thelaser to fully remove the desired portion of the lens. Using someembodiments of the systems and methods described here, grade 3 and/orgrade 4 nuclear cataracts can be sufficiently fragmented such that theycan be aspirated with no phacoemulsification, resulting in a 100%reduction in CDE.

In addition, the systems and methods described here can increase theenergy parameter space available to surgeons performing cataractsurgery. Due at least in part to the higher available energies for usein high NA zones, there is a greater range of energies a surgeon can usewhen performing laser lens fragmentation. This can provide an ability tofragment the lens more effectively and/or more efficiently.

Laser Systems

FIGS. 3A-3C illustrate example laser systems 300 that can be used toprovide a varying numerical aperture for use with some embodiments of alens fragmentation procedure. The laser systems 300 can be configured toprovide two numerical apertures, three numerical apertures, tennumerical apertures, or any number of numerical apertures including asubstantially continuous range of numerical apertures within functionallimits of the various systems. The laser systems 300 can be pulsed lasersystems, such as, for example, femtosecond lasers or picosecond lasers.Other pulse widths may be suitable as well. The laser systems 300 can beconfigured to deliver near infrared light. Other wavelengths may be usedas well. The laser systems 300 can be configured to deliver laser lightfocused at a focus depth which may be controlled by the system. In someembodiments, the lasers 300 include imaging systems as well, such asvideo imaging and/or optical coherence tomography. The laser systems 300can be used in conjunction with a patient interface 350. In someembodiments, the patient interface 350 can be a liquid interfaceconfigured to substantially maintain a shape of the patient's eye whilemaintaining it in substantially the same location and/or orientation.Any suitable patient interface 350 can be used including, for example,liquid interfaces, applanation lenses, deformable contact lenses, or nopatient interface.

In some embodiments, a pulsed laser (e.g. a femtosecond laser) can beused to segment and fragment a lens by ablating a pattern onto thetargeted area of the lens. The lens segmentation and fragmentation canbe accomplished through a variety of methods and generally include, forexample, determining areas or patterns to cut on the lens, selectinglaser energies, selecting or determining a numerical aperture to use forcutting the various areas of the lens, and delivering the laser beamhaving the determined energy and/or numerical aperture to spots alongthe designated cut locations. The energy, frequency and the duty cycleof the pulsed lasers can be varied to produce laser segmentation orfragmentation that is sized and shaped to remove the diseased lens fromthe patient's eye.

FIG. 3A illustrates a laser system comprising a laser engine 302 and abeam delivery device 330. The laser engine 302 can be configured togenerate the laser pulses used for laser lens fragmentation. The laserengine 302 can include a laser source 304, optical components 306, and abeam steering monitor 308. The components of the laser engine 302 can beconfigured to generate the desired laser pulse of a desired energy.

The laser system 300 can include a beam delivery device 310 configuredto adjust properties of the laser pulse prior to delivery to the patientat the patient interface 350. The beam delivery device 310 can include arange finding camera 312 that can be configured to determine a lenssurface and/or orientation. The range finding camera 312 can beconfigured to determine a depth of the anterior chamber and a locationof the lens relative to the anterior chamber of the patient's eye. Thebeam delivery device 310 can include a beam monitor 314 configured toprovide feedback related to properties of the laser as delivered by thelaser engine 302.

To change a numerical aperture of the laser beam, the beam deliverydevice 310 can include a mechanism for switching between a highnumerical aperture and a low numerical aperture. The beam deliverydevice 310 can include a low NA insert 316 that, when inserted into thebeam path, changes the numerical aperture of the laser beam to be arelatively low numerical aperture. When the low NA insert 316 is out ofthe beam path, the laser beam can be configured to deliver a laser beamwith a relatively high numerical aperture.

The beam delivery device 310 includes an x-y shutter 318 configured toscan the laser beam across two dimensions. In some embodiments, the twodimensions can be parallel to the iris. In some embodiments, the twodimensions can lie in another direction.

The beam delivery device 310 can include a video camera 320 configuredto provide visual feedback regarding the target, the laser beam, orboth. The beam delivery device can include an objective lens 322configured to focus the laser beam to a spot. During laser lensfragmentation, the objective 322 can be configured to focus the laserspot within the lens to ablate, cut, or fragment the lens tissue.

FIG. 3B illustrates another example embodiment of a dual-NA laser system300 configured to deliver a pulsed laser to a targeted lens of apatient. Similar to the laser system in FIG. 3A, the laser system 300includes a laser source 302, range finder 312, X-Y scanner 318, and anobjective 322. These components perform generally the same functions asthe laser system in FIG. 3A.

The laser system 300 of FIG. 3B includes a high NA insert 317 that isconfigured to generate a laser beam with a high numerical aperture whenit is in the beam path. When the high NA insert 317 is not in the beampath, the laser system 300 is configured to deliver a laser beam with alow numerical aperture.

The laser systems 300 of FIGS. 3A and 3B can be configured to rapidlyswitch between a low NA laser beam and a high NA laser beam. Forexample, the low NA insert 316 of FIG. 3A or the high NA insert 317 ofFIG. 3B can be configured to be switched in and out of the beam pathwith a typical time of about 1 us or less. In some embodiments, the lowNA insert 318, the high NA insert 317, or both can include a waveplatethat can be opto-mechanically switched such that in a firstconfiguration, the laser beam is polarized in such a way that opticalelements selectively deliver a laser beam with a high NA to theobjective 322, and in a second configuration, the laser beam ispolarized in such a way that the optical elements selectively deliver alaser beam with a low NA to the objective 322. Other methods ofnumerical aperture switching is possible, such as electro-mechanicalswitching, optical switching, polarization switching, and the like.

FIG. 3C illustrates a laser system 300 that is configured to provide asubstantially continuously variable numerical aperture. The laser system300 includes a laser 302 and optical elements 306 along with X-Y scangalvanometer mirrors 318, and an objective 322. The laser system 300includes a video camera, illumination, or fixation system 320 configuredto provide light, video feedback, or other information about the laserbeam. The laser 300 includes a zoom beam expander z-scan configured toadjust the beam width and to adjust a depth of focus.

The laser system 300 includes the variable NA module 316 that isconfigured to provide a substantially continuously variable NA over arange of numerical apertures. The variable NA module 316 can includeoptical components, electrical components, and/or mechanical componentsconfigured to continuously adjust beam parameters to provide asubstantially continuous variable numerical aperture. For example, thevariable NA module 316 can be a telescope that includes a plurality oflenses configured to move relative to each other and to provide avariable numerical aperture.

The laser system 300 includes a confocal module 324 configured toprovide depth-selection capabilities to the laser system 300. The lasersystem 300 includes an OCT module 326 configured to provide opticalcoherence tomography images to the system 300. These images can be usedto generate images of the patient's eye, to determine the geometry ofthe patient's eye, and/or to generate laser treatment plans based on theimages of the patient's eye.

Example Laser Cataract Surgery Control System

FIG. 4 illustrates a block diagram of an example laser cataract surgerycontrol system 400 in communication with a laser system 300 and animaging system 422. The laser cataract surgery control system 400 can beconfigured to determine treatment regions within a lens of a patient, todetermine a safety zone within the lens, to determine a numericalaperture of a laser beam to deliver to identified treatment regions, todetermine a laser energy to deliver to the treatment regions, to receiveimage data from the imaging system 422, to analyze the received imagedata, to control the laser system 300 to deliver laser energy asdetermined by the system 400, and the like.

The laser cataract surgery control system 400 includes a controller 412,data storage 414, a laser control module 416, a fragmentation module418, and an image processing module 420. The various components of thelaser cataract surgery control system 400 can communicate with externalsystems and each other using communication bus 405. Communicationbetween the laser cataract surgery control system 400, the laser system300, and/or the imaging system 422 can occur using wired or wirelesscommunication, and using any suitable protocol.

The controller 412 can include hardware, software, and/or firmwarecomponents used to control the laser cataract surgery control 400. Thecontroller 412 can be configured to receive information from the imagingsystem 422, to receive user input from a user interface component, todetermine treatment zones, and to determine laser parameters. Thecontroller 412 can include modules configured to control the attachedcomponents and analyze received information. The controller 412 caninclude one or more physical processors and can be used by any of themodules within the system 400 to process information. The laser cataractsurgery control 400 can include data storage 414 for storing receivedinformation, control parameters, executable programs, and other suchinformation. Data storage 414 can include physical memory configured tostore digital information and can be coupled to the other components ofthe laser cataract surgery control system 400.

The laser cataract surgery control system 400 includes the imageprocessing module 420. The image processing module 420 can be configuredto receive image information from the imaging system 422, from datastorage 414, and/or from user input. The image processing module 420 canbe configured to analyze the received images to determine structures ofthe eye and their associated locations and/or sizes. For example, theimage processing module 420 can determine a pupil of the patient's eye,the lens, the cornea, and the like with their sizes and/or locations.The image processing module 420 can be configured to provide real-timefeedback to the control system 400 to adjust laser delivery based atleast in part on changes to the patient's eye. The image processingmodule 420 can be configured to provide information regarding the laserbeam being delivered to the patient where the information can be used asfeedback in the laser control module 416 to adjust laser deliveryproperties based at least in part on the feedback information. Theimaging system 422 can be any suitable imaging system for use with alaser cataract surgery system 400 including, but not limited to, OCTsystems, video cameras, LCI systems, or other similar systems. Theimaging system 422 can deliver real-time image data to the controlsystem 400 for processing, or the image data can be provided not in realtime. The laser cataract surgery control system 400 can be configured tooperate without image data from the imaging system 422, or withoutanalyzing any image data. For example, a user can use the laser cataractsurgery control to perform laser lens fragmentation without the controlsystem 400 analyzing image data and/or without the control system 400determining structures within the patient's eye. In some embodiments, auser identifies properties of the patient's eye and inputs thisinformation into the control system 400.

The laser cataract surgery control 400 includes the fragmentation module418. The fragmentation module 418 can be configured to determine regionswithin the lens for laser delivery. For example, the fragmentationmodule can determine a safety zone where no focused radiation is to bedelivered and fragmentation zones where focused laser radiation is to bedelivered. Within the fragmentation zones, the fragmentation module 418can use the controller 412 to determine a high NA zone and a low NAzone. The high NA zone, as described here, can be the zone of the lenswhere the laser system 300 will deliver a high NA beam. Similarly, thelow NA zone can be the zone of the lens where the laser system 300 willdeliver a low NA beam. The fragmentation module 418 can be configured todetermine any number of fragmentation zones.

The fragmentation module 418 can be configured to receive informationregarding the structure of the patient's eye from the image processingmodule 420, a user input system, another external system, or anycombination of these. Based at least in part on the image analysisinformation, the fragmentation module 418 can determine a treatment planor treatment algorithm that includes planned fragmentation locations,fragmentation patterns, fragmentation depths, fragmentation volumes, andthe like. For example, the fragmentation module 418 can determine to usea pie-cut treatment (e.g., cuts extending radially outward from acentral location), a grid treatment (e.g., cuts extending alongsubstantially straight lines along vertical and/or horizontaldirections), or some other treatment. The treatment can be determined bythe fragmentation module 418 or it can be selected by a user. Thefragmentation module 418 can develop a treatment plan with detailsrelated to a size of the cuts, a distance between laser pulses, theenergy of the laser pulses, and the like.

The fragmentation module 418 can be configured to determine a numericalaperture for the laser beam being delivered to a particularfragmentation zone. As described here, the numerical aperture can beselected based on safety considerations, iris shadowing, cataracthardness, cataract location, laser system properties, and the like. Insome embodiments, the fragmentation module 418 is configured todetermine a first treatment zone to be treated by a laser beam with arelatively high numerical aperture. The fragmentation module 418 can beconfigured to determine a maximum size of this region based at least inpart on iris shadowing effects. The fragmentation module 418 can then beconfigured to select a laser energy for delivery to this region. In someembodiments, the laser energy is a fixed value or is selected from arange of values that is independent from the selection of the numericalaperture and/or the fragmentation zones.

An example of a determination of fragmentation zones is shown inTable 1. Table 1 shows allowed lateral dimensions for lens fragmentationrelative to pupil diameter. In the table, a safety zone of 0.5 mm on theedge of the pupil is used. As an example, using a pupil diameter of 7.5mm, a laser beam with a numerical aperture of 0.3 can be made tofragment a lens where the fragmentation can occur over an area with adiameter of about 4.7 mm at a depth of about 4 mm from the pupil. A lowNA laser beam can then be used to fragment the lens out to about a 5.8mm diameter.

TABLE 1 lens fragmentation lateral dimension at a depth H = 4.0 mm d(mm), lens frag. diameter NA at depth H 0.125 0.2 0.25 0.30 0.35 0.400.45 0.50 Pupil 5.0 3.3 2.8 2.5 2.2 1.9 1.6 1.3 0.9 diameter 5.5 3.8 3.33.0 2.7 2.4 2.1 1.8 1.4 (mm) 6.0 4.3 3.8 3.5 3.2 2.9 2.6 2.3 1.9 6.5 4.84.3 4.0 3.7 3.4 3.1 2.8 2.4 7.0 5.3 4.8 4.5 4.2 3.9 3.6 3.3 2.9 7.5 5.85.3 5.0 4.7 4.4 4.1 3.8 3.4 8.0 6.3 5.8 5.5 5.2 4.9 4.6 4.3 3.9 8.5 6.86.3 6.0 5.7 5.4 5.1 4.8 4.4 9.0 7.3 6.8 6.5 6.2 5.9 5.6 5.3 4.9 9.5 7.87.3 7.0 6.7 6.4 6.1 5.8 5.4 10.0 8.3 7.8 7.5 7.2 6.9 6.6 6.3 5.9

Table 1 can be derived based at least partly on geometrical and physicalconsiderations. For example, by considering the pupil diameter, D,safety zone, S, the depth of lens fragmentation, H, the refractive indexof the lens, n, and the numerical aperture, NA, the diameter of lensfragmentation, d, can be determined using the equation:d=D−2S−2H*tan(θ) where θ=a sin(NA/n).  (1)

Thus, the fragmentation module 418 can use an algorithm employing asimilar equation to equation (1) and/or values as demonstrated in Table1 to determining laser fragmentation zones.

The laser cataract surgery control system 400 includes the laser controlmodule 416 configured to control the laser system 300, to sendinstruction to the laser control system 300, or to generate instructionsfor a user to control the laser system 300. The laser control module 416can be configured to control the laser system 300 according to the laserparameters determined by the fragmentation module 418.

Example Laser Fragmentation Procedure

FIG. 5 illustrates a flow chart of an example method 500 for performinga laser fragmentation procedure using a varying numerical aperture laserbeam. The method 500 can be performed by any of the systems describedhere, including the laser cataract surgery control system 400 describedwith reference to FIG. 4. For ease of description, the method 500 willbe described as being performed by a surgery control system, which canbe similar to the control system 400. However, any step or combinationof steps of the method 500 can be performed by any system or combinationof systems or system components.

In block 505, the surgery control system measures features of an eye ofa patient to find a total laser treatment region. The surgery controlsystem can measure the features based at least in part on real-timemeasurements involving surgeon input, image analysis, or both. In someembodiments, the surgery control system determines, for example, a sizeor location of the patient's pupil (e.g., a pupil diameter), a size orlocation of the patient's lens, a size or location of the patient'scornea, an anterior boundary of the lens, a posterior boundary of thelens, or any combination of these.

In block 510, the surgery control system determines a safety zonecomprising a region of the eye of the patient which will not receivefocused laser radiation. The safety zone can be a region of the lens ofthe patient's eye comprising a volume that is a selected distance fromstructures within the patient's eye. For example, the safety zone can bedefined as a distance inwards from an edge of an iris of the patient'seye, a distance from an anterior lens capsule, and a distance from aposterior lens capsule. The distance can be, for example, at least about0.1 mm and/or less than or equal to about 2 mm from these structures, atleast about 0.25 mm and/or less than or equal to about 1 mm from thesestructures, or at least about 0.3 mm and/or less than or equal to about0.75 mm from these structures.

In block 515, the surgery control system determines a high NA zone, thehigh NA zone configured to be a region where a cone angle of a laserbeam with a high numerical aperture is not shadowed by an iris of thepatient's eye. The numerical aperture can be selected, for example, toconform to safety requirements and/or to result in lens tissueseparation in the high NA zone. In some embodiments, the high numericalaperture is at least about 0.2 and/or less than or equal to about 0.6,at least about 0.25 and/or less than or equal to about 0.55, at leastabout 0.3 and/or less than or equal to about 0.5, or at least about 0.3and less than or equal to about 0.4.

In block 520, the surgery control system determines a low NA zone, thelow NA zone configured to be a region radially closer to the iris thanthe high NA zone where the cone angle of the laser beam with a lownumerical aperture is not shadowed by the iris. In some embodiments, thehigh NA zone, the low NA zone, and the safety zone can be configured tooccupy, in aggregate, approximately the entirety of the total lasertreatment region. In some embodiments, the low numerical aperture is atleast about 0.075 and/or less than or equal to about 0.25, at leastabout 0.1 and/or less than or equal to about 0.2, at least about 0.125and/or less than or equal to about 0.175, or at least about 0.125 andless than or equal to about 0.15.

In some embodiments, additional zones can be determined for delivery oflaser energy for laser fragmentation. As described here, the number ofzones can be greater than two and the zones can be configured to eachhave a laser beam with a particular numerical aperture deliveredthereto. As described elsewhere here, the numerical aperture and energyof the laser to be used for lens fragmentation can be represented usinga substantially continuous function that is expressed as a positionwithin the lens. In this way, a continuously variable NA laser can beused to deliver improved or optimized laser energy as a function ofposition to improve or maximize fragmentation within the lens.

In block 525, the surgery control system delivers the laser beam withthe high numerical aperture to the high NA zone. Delivery of the high NAlaser beam can be accomplished using any of the laser systems describedhere, such as the laser systems described with reference to FIGS. 3A,3B, and 3C. The high NA laser beam can be configured to deliver a laserenergy sufficient to cause tissue separation in the lens, and in someembodiments, to cause lens tissue separation in a grade 3 or grade 4nuclear cataract. The high NA laser beam can be configured to deliver amaximum peak energy to a retina of the patient's eye that is less than asafety threshold.

In block 530, the surgery control system delivers the laser beam withthe low numerical aperture to the low NA zone. The low NA laser beam canbe configured to deliver a laser energy sufficient to cause tissueseparation in the periphery of the lens. The low NA laser beam can beconfigured to deliver a maximum peak energy to a retina of the patient'seye that is less than a safety threshold.

In some embodiments, a position of the laser beam is tracked with alaser scanning system comprising a plurality of galvanometer mirrors. Insome embodiments, delivering the laser beam includes using anelectro-mechanical system to adjust a set of lens elements to adjust anumerical aperture of the laser beam when delivery of the laser beampasses between the high NA zone and the low NA zone.

In some embodiments, the laser lens fragmentation method 500 can be usedto reduce or eliminate an amount of CDE during phacoemulsification. Forexample, the reduction in the amount of CDE during phacoemulsificationfor grade 3 cataracts can be greater than about 50%, greater than about60%, greater than about 70%, greater than about 80%, greater than about90%, or about 100%. In some embodiments, phacoemulsification can beeliminated through the use of the method 500. For example, sufficientlaser energy can be delivered to a lens to sufficiently cut the lenssuch that the fragmented lens can be aspirated without applying anyultrasonic energy. In some embodiments, the method 500 can be used tosufficiently fragment grade 3 and/or grade 4 nuclear cataracts such thatthey can be aspirated with no phacoemulsification, resulting in a 100%reduction in CDE.

Much of the description here is in the context of laser lensfragmentation during laser cataract surgery. However, the systems andmethods described here may be applicable to any laser treatment orsurgery applied to the lens of the eye, where shadowing from the irismay affect delivery of laser energy. Furthermore, the systems andmethods described here may be applicable to laser treatment of a lens ina patient's eye where retinal safety standards are a concern, wherelaser efficiency is a concern, and/or where efficacy of treatment is aconcern. For example, refractive surgery may be performed at the lensbehind the iris. For such procedures, using a varying numerical apertureduring delivery of the laser may be advantageous to increase theefficiency of the procedure, to increase precision, to reduce retinaldamage, and the like. As another example, lens index modification ormodification of intraocular lenses can be accomplished with lasers whereshadowing by the iris may affect the delivery of the laser to a target.The systems and methods described here may be used for these proceduresas well. Thus, it is to be understood that the disclosed embodimentsshould not be restricted solely to laser lens fragmentation, and can beused for a variety of applications that deliver laser to locationsbehind the iris of a patient's eye.

Although the invention has been described and pictured in an exemplaryform with a certain degree of particularity, it should be understoodthat the present disclosure of the exemplary form has been made by wayof example, and that numerous changes in the details of construction andcombination and arrangement of parts and steps may be made withoutdeparting from the spirit and scope of the invention as set forth in theclaims hereafter.

As used here, the term “processor” refers broadly to any suitabledevice, logical block, module, circuit, or combination of elements forexecuting instructions. For example, the controller 412 can include anyconventional general purpose single- or multi-chip microprocessor suchas a Pentium® processor, a MIPS® processor, a Power PC® processor, AMD®processor, or an ALPHA® processor. In addition, the controller 412 caninclude any conventional special purpose microprocessor such as adigital signal processor. The various illustrative logical blocks,modules, and circuits described in connection with the embodimentsdisclosed here can be implemented or performed with a general purposeprocessor, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA), orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described here. Controller 412 can be implementedas a combination of computing devices, e.g., a combination of a DSP anda microprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

Data storage 414 can refer to electronic circuitry that allowsinformation, typically computer or digital data, to be stored andretrieved. Data storage 414 can refer to external devices or systems,for example, disk drives or solid state drives. Data storage 414 canalso refer to fast semiconductor storage (chips), for example, RandomAccess Memory (RAM) or various forms of Read Only Memory (ROM), whichare directly connected to the communication bus or the controller 412.Other types of memory include bubble memory and core memory. Datastorage 414 can be physical hardware configured to store information ina non-transitory medium.

Methods and processes described here may be embodied in, and partiallyor fully automated via, software code modules executed by one or moregeneral and/or special purpose computers. The word “module” can refer tologic embodied in hardware and/or firmware, or to a collection ofsoftware instructions, possibly having entry and exit points, written ina programming language, such as, for example, C or C++. A softwaremodule may be compiled and linked into an executable program, installedin a dynamically linked library, or may be written in an interpretedprogramming language such as, for example, BASIC, Perl, or Python. Itwill be appreciated that software modules may be callable from othermodules or from themselves, and/or may be invoked in response todetected events or interrupts. Software instructions may be embedded infirmware, such as an erasable programmable read-only memory (EPROM). Itwill be further appreciated that hardware modules may comprise connectedlogic units, such as gates and flip-flops, and/or may comprisedprogrammable units, such as programmable gate arrays, applicationspecific integrated circuits, and/or processors. The modules describedhere can be implemented as software modules, but also may be representedin hardware and/or firmware. Moreover, although in some embodiments amodule may be separately compiled, in other embodiments a module mayrepresent a subset of instructions of a separately compiled program, andmay not have an interface available to other logical program units.

In certain embodiments, code modules may be implemented and/or stored inany type of computer-readable medium or other computer storage device.In some systems, data (and/or metadata) input to the system, datagenerated by the system, and/or data used by the system can be stored inany type of computer data repository, such as a relational databaseand/or flat file system. Any of the systems, methods, and processesdescribed here may include an interface configured to permit interactionwith users, operators, other systems, components, programs, and soforth.

This disclosure is provided in an exemplary form with a certain degreeof particularity, and describes the best mode contemplated of carryingout the invention to enable a person skilled in the art to make and/oruse embodiments of the invention. The specific ordering and combinationof the processes and structures described are merely illustrative. Thoseskilled in the art will understand, however, that various modifications,alternative constructions, changes, and variations can be made in thesystem, method, and parts and steps thereof, without departing from thespirit or scope of the invention. Hence, the disclosure is not intendedto be limited to the specific examples and designs that are described.Rather, it should be accorded the broadest scope consistent with thespirit, principles, and novel features disclosed as generally expressedby the following claims and their equivalents.

What is claimed is:
 1. A laser cataract surgery control systemcomprising: a laser source configured to emit a laser beam; a controllercomprising one or more physical processors; a fragmentation moduleconfigured to use the one or more physical processors to determine alaser lens fragmentation treatment plan by determining: a first regionof a lens of a patient's eye to receive a first focus of the laser beamhaving a first numerical aperture; and a second region of the lens ofthe patient's eye to receive a second focus of the laser beam having asecond numerical aperture, the second numerical aperture being lowerthan the first numerical aperture, and the second region being radiallycloser, on average, to an iris of the patient's eye than the firstregion; a laser control module in communication with the laser sourceand configured to: control the laser source to deliver the laser beamhaving the first numerical aperture and a first energy to the firstregion of the lens; and control the laser source to deliver the laserbeam having the second numerical aperture and a second energy to thesecond region of the lens without delivering the laser beam having thefirst numerical aperture and the first energy to the second region ofthe lens, wherein the first numerical aperture and the first energy areconfigured to deliver a first peak laser energy to a retina of thepatient's eye that is less than or equal to a safety threshold.
 2. Thecontrol system of claim 1, wherein the second numerical aperture and thesecond energy are configured to deliver a second peak laser energy tothe retina that is less than or equal to a safety threshold.
 3. Thecontrol system of claim 1, wherein the laser source is a pulsed lasersource.
 4. The control system of claim 1, wherein the safety thresholdis determined based at least partly on a safety standard involving amaximum permissible radiant exposure.
 5. The control system of claim 4,wherein the safety standard conforms to ANSI Z136.1-2000 Standard. 6.The control system of claim 1, further comprising an image processingmodule in communication with an imaging system, the image processingmodule configured to: receive an image of the patient's eye; determine,using the at least one physical processor, a size of a pupil of thepatient's eye; and determine, using the at least one physical processor,a relative location and size of the lens of the patient's eye.
 7. Thecontrol system of claim 6, wherein the imaging system is an opticalcoherence tomography system.
 8. The control system of claim 6, whereinthe fragmentation module is configured to receive the size of the pupiland the size of the lens of the patient's eye from the image processingmodule, wherein the fragmentation module is configured to use the sizeof the pupil and the size of the lens to determine the first region andthe second region.
 9. The control system of claim 8, wherein the firstregion is configured to maximize a volume in the lens where the laserbeam having the first numerical aperture is used to perform laser lensfragmentation, wherein a maximum radius of the first region from thecenter of the lens of the patient's eye is determined by a shadowingeffect caused by the iris of the patient's eye.
 10. The control systemof claim 1, wherein the fragmentation module is further configured todetermine a safety zone that is, on average, closer to the iris of thepatient's eye than the second region, wherein the safety zone comprisesa region of the lens where the control system does not delivery focusedlaser energy.
 11. The control system of claim 1, wherein thefragmentation module is further configured to determine a third regionof the lens of the patient's eye to receive the laser beam having athird numerical aperture, the third region being between the firstregion and the second region, and the third numerical aperture beingless than the first numerical aperture and greater than the secondnumerical aperture.
 12. The control system of claim 1, wherein the firstnumerical aperture is greater than or equal to 0.25.
 13. The controlsystem of claim 1, wherein the second numerical aperture is less than orequal to 0.15.
 14. The control system of claim 1, wherein the firstnumerical aperture is equal to 0.3.
 15. The control system of claim 1,wherein the second numerical aperture is equal to 0.125.
 16. The controlsystem of claim 1, wherein the first numerical aperture is based atleast partly on a cataract grade.
 17. The control system of claim 1,wherein after delivery of the laser beam with the first numericalaperture to the first region and after delivery of the laser beam withthe second numerical aperture to the second region, the lens of thepatient's eye is sufficiently fragmented such that nophacoemulsification is required to remove the fragmented portion of thelens.
 18. The control system of claim 1, wherein the first region isgenerally cylindrical in shape with a center approximately at a centerof the lens, and the second region is generally annular with a minimumradius approximately equal to a radius of the first region.